1. Field of the Invention
This invention relates to an exposure control mode selecting device for multi-mode automatic exposure control cameras having various automatic exposure control modes, and more particularly to an exposure control mode selecting device capable of selecting at least one particular program line out of a plurality of program lines concerning combinations of shutter time and aperture values for one mode.
2. Description of the Prior Art
A wide variety of multi-mode automatic exposure control cameras switchable from one of the shutter speed priority, aperture priority and program exposure control modes to another one have been put into practice. In the cameras of this kind it has also been the common practice that the selected one of the exposure control modes is displayed in the form of a letter or symbol. Such discrimination of the display by the letter or symbol is, however, inconvenient when to recognize what it implies. Particularly for the beginner, or the user who does not have the ability to choose appropriate values of shutter speed and aperture for obtaning a desired image effect which differs with different depths of focus or different shutter speeds, or does not yet acquire the knowledge of correlations of aperture value, shutter time, film sensitivity and object brightness, it is very difficult to determine the values of aperture and shutter time in view of the desired image effect. In this respect, despite what mode operates is indicated, the use of letters or symbols in the display does not help such a user in his difficulty of choosing an appropriate combination of shutter time and aperture values while getting a fair insight into what image effect will result. As any image effect will be obtained when the exposure factors have values falling within ranges, these ranges are also not indicated in the conventional cameras of the kind described above. To show an example, if the display of the aperture priority exposure mode is presented by "A" or "Av", for the pan-focus effect is obtained, what aperture value has to be chosen is left unknown. And, in what range of object brightness the pan-focus effect can be obtained is also unknown.
To overcome this, that is to say, in order even for the beginner to make photographs by taking into account the image effect owing to the combination of shutter speed and aperture values, the corresponding combinations of shutter speed and aperture values to the various image effects are previously programmed in the camera and the image effects these programs produce are represented by simple pictorial symbols or pictographs as displayed either within the finder or on the top panel of the camera housing. However, what is merely said of the image effect is not unequivocally defined. So, whatever good a pictograph is cannot always express 100% of the intended image effect, depending on the speed of movement of the object, the distance between the subject of principal interest and the background, and the focal length of the photographic lens. This should be explained in more detail by taking an example of stop motion. For ski competitions, car races, or fast moving objects, faster shutter speeds than 1/500 sec. must be chosen. Otherwise, the image effect of stop motion could not be produced. But, to slow moving objects such as running pupils, 1/250 sec. or less suffices for obtaining the effect of stop motion. Considering the case when the camera is used by the beginner, we hardly expect him to notice the difference in the photographic situation and the focal length of the lens and then to make determination of the most appropriate combination of shutter speed and aperture values. Therefore, we have to find as many combinations of shutter speed and aperture values as possible which are well suited to produce the various image effects and to program them in the camera so that even the beginner can shoot the camera to every photographic situation which may be encountered with the result that the percentage of photographs which will be found unacceptable is greatly reduced. From the point of view of the quick and easy management of the camera, however, if several programs for the same image effect are assigned to one exposure control mode, when to determine which program is most suited to the given photographic situation, the beginner will put into confusion after all. This is the same thing as only one program is assigned to one exposure control mode, namely, the shutter priority or the aperture priority one. The use of this method, therefore, not only increases the difficulty of handling camera, but also makes the user to miss shutter chances with increased possiblity.